MOSCOW, SEPT. 16 -- Forty-one British students here have been tested for AIDS antibodies in the first application of requirements that long-term foreign visitors be screened, a British Embassy spokesman said today.

A law passed last month to counter the spread of acquired immune deficiency syndrome gives authorities the right to test the blood of foreigners who will be studying or working in the Soviet Union at least three months.

Despite the prompt British compliance, spokesmen in the embassies of the United States, West Germany and other Western European countries said their citizens would not be tested until Soviet authorities clarified the terms of the program.

The major concern expressed by western embassies is that blood tests here have been done with reusable needles, which can spread the virus. The British Embassy provided Soviet authorities with disposable needles and obtained agreement that a British doctor would be present during the testing.

Disposable needles were sent for British students in Voronezh but no British doctor could be present there.

Another worry is that by focusing on foreigners for tests the Soviet Union may be impeding contacts between Soviets and westerners. Soviet authorities have not specified any group of Soviets, as opposed to foreigners, who will be subject to tests.

David Lewis, one of the British students tested yesterday, said today that the testing of foreigners is "irrelevant. AIDS is here already. It's not going to make any difference now."

The anti-AIDS law, considered strict by westerners, calls for jail terms of up to five years for those infected with the virus who have sex, even if they do not show signs of illness. Those found to pass on the virus can be jailed for up to eight years.

Of the 132 reported cases of persons in the Soviet Union found to be carrying the virus, the majority are foreigners, according to official Soviet accounts. The deaths of three African students here have been reported.

While the campaign against the disease has appeared to focus largely on foreigners, one exception is the case of "Lyudmila" of Leningrad.

Infected with the AIDS virus, Lyudmila was made to sign a statement saying she would not have sex with anyone for five years, according to a dispatch by the official news agency Tass on Friday. She was warned about her responsibilities if she violated the agreement, Tass said, which could include a jail term of up to eight years.